Casualties unknown

1991-02-18: Hughes 269C (N8973F) — Stanley J. Barby — Knowles, OK

Knowles, OK, US

On February 18, 1991, a Hughes 269C (registration N8973F) operated by Stanley J. Barby was involved in an aviation accident near Knowles, OK. Investigators recorded the probable cause as: The pilot's inability to arrest an excessive sink rate during a practice autorotation in gusty wind conditions, resulting in a hard landing. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.

Sourcesthe U.S. National Transportation Safety Board (NTSB) historical archivePrimary reportUpdated 1781061362Data APIEditorial standards

A helicopter pilot attempted a practice autorotation from 1,000 feet AGL but could not arrest an excessive sink rate in gusty winds, resulting in a hard touchdown.

What happened

The pilot initiated a maneuver to conduct a practice autorotation, targeting a pasture for the landing phase. The operation began from an altitude of approximately 1,000 feet above ground level. Environmental conditions during the attempt were characterized by gusty winds, which likely contributed to the difficulty in maintaining stable flight parameters.

During the execution of the maneuver, the helicopter developed an excessive sink rate. Recognizing the situation, the pilot attempted to abort the autorotation and execute a go-around. Power was applied in an effort to arrest the descent; however, the aircraft was unable to stop the downward momentum before impacting the ground. The result was a hard touchdown.

The investigation

The factual narrative provided indicates that the primary mechanical or operational failure was the inability to arrest the sink rate despite power application. No specific mechanical defects were cited in the source text, pointing instead to the aerodynamic challenges presented by the maneuver and weather conditions.

Probable cause

The pilot's inability to arrest an excessive sink rate during a practice autorotation in gusty wind conditions, resulting in a hard landing.

Investigation report by the U.S. National Transportation Safety Board (NTSB) historical archive. Original record: https://carol.ntsb.gov/event/20001212X16455. This page is a structured re-presentation; facts and quotes are in the National Transportation Safety Board (NTSB), United States.